KR20220065732A - Light-emitting device - Google Patents

Abstract

The present invention provides a light emitting device using a quantum dot, specifically, a green quantum dot, and, also, having high light emitting efficiency. The light emitting device includes: a light emitting element emitting blue light; the quantum dot absorbing a part of the blue light emitted by the light emitting element, and emitting green light; and at least one of a KSF fluorescent body and an MGF fluorescent body. The KSF fluorescent body, which is represented by chemical formula 1, A_2 [M_1-a Mn^4+_aF_6], emits red light by absorbing a part of the blue light emitted by the light emitting element. The MGF fluorescent body, which is represented by chemical formula 2, (x-a) MgO ∙ (a/2) Sc_2O_3 ∙ yMgF_2 ∙ cCaF_2 ∙ (1-b) GeO_2 ∙ (b/2) Mt_2O_3 : zMn^4+, emits the red light by absorbing a part of the blue light emitted by the light emitting element.

Description

Light-Emitting Device {LIGHT-EMITTING DEVICE}

The present disclosure relates to a light emitting device, particularly a light emitting device including a light emitting device that emits blue light, and a quantum dot that absorbs a part of the blue light emitted by the light emitting device and emits green light.

A light emitting device for emitting white light, comprising: a light emitting element emitting blue light; A light emitting device including a red phosphor that absorbs a part of blue light emitted by a light emitting element and emits red light has been conventionally known. The light emitting device that emits such white light is used for various purposes including backlights and lighting devices of various displays such as liquid crystal displays.

Recently, a light emitting device in which all or part of a phosphor is replaced with a quantum dot (QD) has been developed. A quantum dot is a semiconductor particle which has a diameter of several nm - several tens of nm, similarly to a phosphor, absorbs light, such as blue light emitted by a light emitting element, for example, and emits light different from the absorbed light.

A green quantum dot that does not contain a green phosphor and a red phosphor, which absorbs blue light emitted by the light emitting element and emits green light, and a red quantum dot that absorbs the blue light emitted by the light emitting element and emits red light A light emitting device comprising a is known. In addition, Patent Document 1 discloses a light emitting device including a yellow-green phosphor and a red quantum dot.

The quantum dot has a characteristic that the emission peak is sharp, that is, the half-width of the emission peak is small (narrow). For this reason, the light emitting device using quantum dots has the advantage that the color reproduction range becomes wide, when combining with color filters, such as a liquid crystal display. In addition, by matching the peak wavelength of the color filter (the wavelength at which the transmittance becomes a peak) with the emission peak of the quantum dot, more light can pass through the color filter. The light extraction efficiency is improved.

In particular, since conventional green phosphors and yellow-green phosphors have broad emission peaks, these effects can be more conspicuously obtained by using green quantum dots.

Japanese Patent Laid-Open No. 2008-544553

However, in the conventional light emitting device using such quantum dots, red quantum dots are used, which has a problem in that secondary absorption occurs. That is, the red quantum dot absorbs a part of the green light (or yellow-green light) emitted by the green quantum dot or green phosphor (or yellow-green phosphor) that has absorbed blue light to emit red light. When such secondary absorption occurs, there is a problem that the luminous efficiency of the entire light emitting device is lowered.

On the other hand, for many applications such as displays and lighting devices, there is a demand for a light emitting device capable of emitting brighter light with less power consumption, that is, a higher luminous efficiency.

The present disclosure has been made in order to meet such a request, and is to provide a light emitting device using quantum dots, particularly green quantum dots, and having high luminous efficiency.

A light emitting device that emits blue light, a quantum dot that absorbs a portion of the blue light emitted by the light emitting device and emits green light, the composition of which is represented by the following Chemical Formula 1, and a portion of the blue light emitted by the light emitting device A KSF phosphor that absorbs and emits red light and its composition is represented by the following formula (2), characterized in that it contains at least one of MGF phosphors that absorb a part of the blue light emitted by the light emitting device and emit red light. It is a light emitting device.

[Formula 1]

(In Formula 1, A is at least one selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ⁴⁺ , and M is composed of a Group 4 element and a Group 14 element. It is at least one element selected from the group, and a satisfies 0<a<0.2.)

[Formula 2]

(In Formula 2, x, y, z, a, b, c are 2.0≤x≤4.0, 0<y<1.5, 0<z<0.05, 0≤a<0.5, 0<b<0.5, 0≤ c<1.5, y+c<1.5, and Mt is at least one selected from Al, Ga, and In)

It is a light emitting device using quantum dots, especially green quantum dots, and it is possible to provide a light emitting device having high luminous efficiency.

1 is a schematic cross-sectional view of a light emitting device 100 according to the first embodiment.
2 is a view showing a preferred chromaticity range of light emitted from the light emitting device package 10 on chromaticity coordinates.
3A is an SEM image showing a part of a cross section of the produced light emitting device package 10 .
3B is an enlarged SEM image of part A of FIG. 3A .
FIG. 3C is an enlarged SEM image of part B of FIG. 3A .
FIG. 3D is an enlarged SEM image of part C of FIG. 3A .
FIG. 3E is an enlarged SEM image of part D of FIG. 3B .
4 is an emission spectrum of the obtained light emitting device package 10 .
5 is a schematic cross-sectional view of a light emitting device 100A according to the second embodiment.
6A is a schematic cross-sectional view for explaining the advantage of the light-emitting device 100 , and shows an embodiment in which the red phosphor 14 is disposed inside the sealing resin 12 .
6B is a schematic cross-sectional view for explaining the advantages of the light-emitting device 100 , and shows an embodiment in which the red phosphor 14 is disposed inside the light-transmitting material 22 .
7 is a schematic cross-sectional view showing a liquid crystal display 200 using the light emitting device 100B according to the third embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings. However, it should be noted that the embodiments described below are for realizing the technical idea of the present invention, and are not intended to limit the technical scope of the present invention. The configuration described in one embodiment is applicable to other embodiments unless otherwise specified. In the following description, terms (for example, "upper", "lower", "right", "left" and other terms including these terms) are used to indicate a specific direction or position as necessary. The use of terms is to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of those terms.

It should be noted that the size, positional relationship, and the like of the members shown in the drawings are exaggerated for clarity of explanation. In addition, the part of the same code|symbol which appears in several drawing shows the same part or member. In addition, for example, a member represented by a code consisting of a number and an alphabet, such as the reference sign "10A", has the same number as, for example, "10", and does not have an alphabet, unless otherwise specified. You may have the same structure as the member represented by the code|symbol and the member represented by the code|symbol which has the same number and a different alphabet.

As a result of intensive studies, the present inventors have used, as a red phosphor, at least one of KSF phosphor and MGF phosphor, instead of using red quantum dots, so that a light emitting device having high luminous efficiency using green quantum dots can be provided. found out that KSF phosphors and MGF phosphors, which will be described in detail later, absorb blue light emitted by the light emitting element and emit red light, but hardly absorb green light emitted by green quantum dots. That is, secondary absorption does not occur. For this reason, the light emitting device according to the embodiment of the present invention has high luminous efficiency. Further, the peaks in the emission spectra of the KSF phosphor and the MGF phosphor have a narrow half-width of about 10 to 20 nm. For this reason, even when a color filter that transmits substantially the entire red wavelength region is passed, red having a narrow half width is obtained, and thus red light having high color purity can be obtained.

In addition, in this specification, a "quantum dot" means a wavelength conversion substance using the quantum size effect of semiconductor fine particles (semiconductor nanoparticles). It is known that semiconductor microparticles exhibit a quantum size effect when the particle diameter is, for example, several tens of nm or less. The quantum size effect refers to a phenomenon in which the respective bands of the valence band and conduction band, which are considered to be continuous in bulk particles, become discrete when the particle size is made into a nano size, and the bandgap energy changes according to the particle size. Since the semiconductor nanoparticles having such a quantum size effect absorb light and emit light corresponding to the band gap energy, they can be used as a wavelength conversion material in a light emitting device.

Hereinafter, a light emitting device according to a plurality of embodiments of the present invention will be described in detail.

1. Embodiment 1

1 is a schematic cross-sectional view of a light emitting device 100 according to the first embodiment. The light emitting device 100 includes a light emitting element 1 emitting blue light, a green quantum dot 24 emitting green light by absorbing a portion of the blue light emitted by the light emitting element 1 , and a light emitting element 1 . A red phosphor 14 that absorbs a part of the blue light emitted by the wig and emits red light is included. The red phosphor 14 is at least one of a KSF phosphor and an MGF phosphor, which will be described in detail later.

In the light emitting device according to the present disclosure, the positional relationship between the red phosphor 14 and the green quantum dot 24 with respect to the light emitting element 1 is not particularly limited. That is, (1) the red phosphor 14 may be located closer to the green quantum dot 24 with respect to the light emitting element 1, (2) the red phosphor 14 may be located closer to the light emitting element 1, It may be located farther than the green quantum dot 24, and (3) as in the second embodiment to be described later, with respect to the light emitting element 1, the red phosphor 14 and the green quantum dot 24 are located at approximately the same distance also be

In Embodiment 1, with respect to the light emitting element 1, the red phosphor 14 side is located closer than the green quantum dot 24. As shown in FIG.

The light emitting device 100 includes a light emitting device package 10 . The light emitting device package 10 includes a resin package 3 having a bottom surface, a side wall, a cavity surrounded by the bottom surface and the side wall, and having an open top, and a light emitting device 1 disposed on the cavity bottom of the resin package 3 . ) and the sealing resin 12 filled in the cavity of the resin package 3 . The light emitting element 1 has a positive electrode and a negative electrode connected to an external power supply through conductive means such as a metal wire, metal bump, plating, etc., and emits blue light by supplying a current (electric power) from the external power supply. .

A lead may be disposed on the bottom surface of the cavity of the resin package 3, and the light emitting element 1 may be disposed on the lead. When a lead is used, the lead and the negative electrode and/or the positive electrode of the light emitting element may be connected with a metal wire, and the light emitting element 1 may be connected to an external power supply through the lead. Moreover, you may flip-chip connection with solder etc., without using a metal wire. In addition, the lead may have a plating layer on the surface as needed.

The sealing resin 12 covers the periphery of the light emitting element 1 (in the embodiment shown in FIG. 1, the upper surface and the side surface except for the bottom surface of the light emitting element 1). The sealing resin 12 contains a red phosphor 14 . That is, the red phosphor 14 is dispersedly arranged inside the sealing resin 12 .

In addition, in the embodiment shown in FIG. 1, although the red fluorescent substance 14 is disperse|distributed uniformly in the sealing resin 12, the form of the dispersion arrangement|positioning of a red fluorescent substance is not limited here. The red phosphor 14 may be disposed at a higher density in a part of the encapsulating resin 12 , for example, in the vicinity of the light emitting element 1 , such as disposed at a high density. As such an arrangement, there is a so-called sedimentation arrangement in which the dispersion density of the red phosphor is small at the top of the sealing resin and high at the bottom of the sealing resin 12 (including directly above the light emitting element 1). In the sedimentation arrangement, for example, the sealing resin 12 before curing, in which the red phosphor 14 is uniformly dispersed, is filled into the cavity of the resin package 3, and then the sealing resin 12 is left uncured for a predetermined time. Then, after the red phosphor 14 in the sealing resin 12 moves by gravity and the distribution becomes high in the bottom of the sealing resin 12, it can form by hardening the sealing resin 12. You may settle by centrifugal force.

Moreover, in addition to the red fluorescent substance 14, you may arrange|position inside the sealing resin 12, a filler.

The light emitting device package 10 emits blue light and red light with its upper surface as an emission surface. In more detail, a part of the blue light emitted from the light emitting element 1 passes through the sealing resin 12 and exits toward the outside from the upper surface of the sealing resin 12. A part of the blue light emitted from the light emitting device package 10 is reflected from the side and/or bottom surface of the resin package 3 as it travels inside the sealing resin 12 , and then is emitted from the upper surface of the sealing resin 12 . You can do it. In addition, another part of the blue light emitted from the light emitting element 1 is absorbed by the red phosphor 14 on the way to the inside of the sealing resin 12, and the red phosphor 14 emits red light. Then, the red light emitted from the red phosphor 14 passes through the sealing resin 12 and is emitted from the upper surface of the sealing resin 12 toward the outside. A part of the red light emitted by these red phosphors 14 may be reflected from the side and/or bottom surface of the resin package 3 when traveling inside the sealing resin 12 , and then emitted from the upper surface of the sealing resin 12 . .

The green quantum dot containing layer 20 is arrange|positioned on the outer side of the sealing resin 12, ie, the upper part of the sealing resin 12 (or the resin package 3) in FIG. 1 . The green quantum dot containing layer 20 includes a light-transmitting material 22 and green quantum dots 24 . That is, the green quantum dots 24 are dispersedly arranged in the light-transmitting material 22 . The green quantum dot-containing layer 20 may have any shape. One of the preferable shapes is a sheet shape (or a film shape) as shown in FIG. 1 . This is because the thickness of the green quantum dot-containing layer 20 can be made uniform and color unevenness can be suppressed.

By having such a configuration, in the light-emitting device 100 , the red phosphor 14 is located closer to the light-emitting element 1 than the green quantum dot 24 . A KSF phosphor or an MGF phosphor having a large particle diameter (or diameter) of, for example, 20 to 50 μm, is disposed near the light emitting element, and green quantum dots 24 having a particle diameter (or diameter) of, for example, 2 to 10 nm ) in the vicinity of the light emitting element 1, it is possible to suppress scattering of light, particularly scattering of green light by the red phosphor 14, and as a result, the light extraction efficiency (ie, luminous efficiency) can be further improved. there is.

About the improvement of this light extraction efficiency, the detail is demonstrated after the structure of Embodiment 2 mentioned later.

Most of the red light emitted from the upper surface of the light emitting device package 10 enters from the lower surface of the green quantum dot-containing layer 20 , passes through the light-transmitting material 22 of the green quantum dot-containing layer 20 , and then becomes green The quantum dot-containing layer 20 goes out from the top surface.

Most of the blue light emitted from the upper surface of the light emitting device package 10 enters the inside from the lower surface of the green quantum dot-containing layer 20 . Part of the blue light entering the inside from the lower surface of the green quantum dot-containing layer 20 passes through the light-transmitting material 22 of the green quantum dot-containing layer 20 and then exits from the upper surface of the green quantum dot-containing layer 20 to the outside. Another part of the blue light entering the inside from the lower surface of the green quantum dot-containing layer 20 is absorbed by the green quantum dot 24, and the green quantum dot 24 emits green light. Most of the green light emitted by the green quantum dots 24 travels inside the translucent material 22 and exits outward from the top surface of the green quantum dot-containing layer 20 . As a result, on the outside of the upper surface of the green quantum dot-containing layer 20 , blue light, red light, and green light are mixed to obtain white light.

In addition, a part of the green light emitted by the green quantum dots 24 goes downward, comes out from the lower surface of the green quantum dot-containing layer 20 , and enters the interior of the sealing resin 12 from the upper surface of the light emitting device package 10 . . However, the red phosphor 14, which is at least one of the KSF phosphor and the MGF phosphor, hardly absorbs green light. For this reason, for example, after being reflected by the inner surface of the resin package 3, it exits from the upper surface of the light emitting device package 10, enters from the lower surface of the green quantum dot containing layer 20, and the green quantum dot containing layer 20 ), there is green light emitted from the upper surface. The presence of such green light contributes to the improvement of the extraction efficiency of the light emitting device 100 .

In the embodiment shown in FIG. 1 , the green quantum dot-containing layer 20 and the sealing resin 12 (or the resin package 3 ) are spaced apart. Thereby, the effect of being able to suppress more reliably that the heat_generation|fever of the light emitting element 1 transmits to the green quantum dot 24 which is weak to heat is acquired.

However, it is not limited to this, The green quantum dot containing layer 20 and the sealing resin 12 (or the resin package 3) may contact. In this case, more light emitted from the light emitting device package 10 enters the green quantum dot-containing layer 20 , and it becomes possible to further increase the extraction efficiency. Further, even if the green quantum dot-containing layer 20 and the sealing resin 12 (or the resin package 3) are in contact with each other, the light emitting element 1 and the green quantum dot 24 are separated from each other to some extent. The effect of suppressing the thermal deterioration of the quantum dot 24 can be acquired.

In the embodiment shown in Fig. 1, the light emitting device package 10 has a bottom surface (lower surface) for its mounting surface, and a surface opposite to the light extraction surface as a mounting surface (for example, the upper surface is referred to as a light extraction surface) and the lower surface is called the mounting surface) It is a top-view type light emitting device package. However, the present invention is not limited thereto, and the light emitting device package 10 may be configured as a so-called side view type in which the surface adjacent to the light extraction surface is used as the mounting surface.

In addition, in embodiment shown in FIG. 1, although the light emitting element package 10 containing the resin package 3 is used, it is not limited to this. Instead of the light emitting device package 10, a so-called unpackaged form in which a phosphor layer containing the red phosphor 14 is formed on the surface of the light emitting device 1 without using a resin package may be used.

FIG. 2 is a diagram showing a preferred chromaticity range of light emitted from the light emitting device package 10 (light incident on the green quantum dot containing layer 20 ) on chromaticity coordinates. The chromaticity of light emitted from the light emitting device package 10 is within the range of a rectangle indicated by a dotted line in FIG. ) and (the range of a rectangle formed by connecting the four points of (0.1706, 0.0157)) is preferable.

The chromaticity of light emitted from the light emitting device package 10 is in the range of a rectangle indicated by a solid line in FIG. 2 (that is, in the xy chromaticity coordinate system of the CIE1931 chromaticity diagram, (0.19, 0.099779), (0.19, 0.027013), (0.3, 0.09111) ) and (0.3, 0.14753) are more preferably within the range of a rectangle formed by connecting the four points).

By making the chromaticity into such a range, when it is used together with the green quantum dot containing layer 20, it is possible to obtain a color tone suitable as a backlight.

An example in which the light emitting device package 10 having the chromaticity of the emitted light within this range was actually manufactured and the emission spectrum was measured is shown below.

3A is an SEM image showing a part of a cross section of the light emitting device package 10 produced, FIG. 3B is an enlarged SEM image of part A of FIG. 3A , FIG. 3C is an enlarged SEM image of part B of FIG. 3A , and FIG. 3D is an enlarged SEM image of FIG. 3A It is an enlarged SEM image of part C, and FIG. 3E is an enlarged SEM image of part D of FIG. 3B.

A resin package 3 having an external dimension of 4 mm in length, 1.4 mm in width, and 0.6 mm in height was used with a substantially rectangular cavity in the corner when viewed from the top. The resin package 3 has a pair of leads 5 on the bottom surface of the cavity, and the leads 5 have a plating layer 15 on the surface. A light-emitting element 1 having a light-transmitting substrate 13 and a semiconductor layer 11 is disposed on one side of the pair of leads 5 . The light emitting element 1 and a pair of leads were electrically connected by a gold wire. The light emitted from the light emitting element 1 has a peak in emission intensity between 435 nm and 465 nm.

The sealing resin 12 was formed by disposing a silicone resin in which the red phosphor 14 and the filler 15 were dispersed in the cavity of the resin package 3, and centrifugally sedimenting the red phosphor 14 and the filler 15. As the red phosphor 14, a KSF phosphor (K ₂ SiF ₆ :Mn ⁴⁺ ) was used. As the filler 15, a silica filler and a nano-silica filler were used. The sealing resin 12 contained about 17 parts by weight of the KSF phosphor, about 5 parts by weight of the silica filler, and about 0.4 parts by weight of the nano-silica filler with respect to 100 parts by weight of the silicone resin.

As shown in FIG. 3C , the upper side of the side surface of the light emitting element 1 was not covered with the red phosphor 14 and the filler 16 .

4 is an emission spectrum of the obtained light emitting device package 10 . The light emitting element 1 mainly emits light with a wavelength of 430 nm to 480 nm, and the red phosphor 14 mainly emits light with a wavelength of 600 nm to 660 nm. It has a 1st peak wavelength which shows the maximum value of the light emission intensity of the light emitting element 1 at 447 nm, and has a 2nd peak wavelength which shows the maximum value of the light emission intensity of the red phosphor 14 at 631 nm. The ratio of the light emission intensity at the first peak wavelength to the light emission intensity at the second peak wavelength is 1st : 2nd = 100:67.

The values of the chromaticity coordinates in CIE1931 were x=0.216 and y=0.054.

Next, details of each element of the light emitting device 100 will be described.

1) Light emitting element

The light-emitting element 1 may be any known light-emitting element or a blue LED chip as long as it emits blue light (the emission peak wavelength is in the range of 435 to 465 nm). The light emitting element 1 may be provided with a semiconductor laminated body, and it is preferable to provide a nitride semiconductor laminated body. A semiconductor laminate (preferably a nitride semiconductor laminate) may have a first semiconductor layer (eg, an n-type semiconductor layer), a light emitting layer, and a second semiconductor layer (eg, a p-type semiconductor layer) in this order do.

As a preferable nitride semiconductor material, specifically, In _X Al _Y Ga _1-XY N (0≤X, 0≤Y, X+Y≤1) may be used. The film thickness and layer structure of each layer may use a thing known in the said field|area.

2) Red phosphor

The red phosphor 14 is at least one of a KSF phosphor and an MGF phosphor. The KSF phosphor and the MGF phosphor have the advantage that they hardly absorb green light and therefore hardly generate secondary absorption. In addition, it is characterized in that the half-width of the emission peak is as small as 35 nm or less, preferably 10 nm or less. Hereinafter, the KSF phosphor and the MGF phosphor will be described in detail.

(KSF phosphor)

The KSF phosphor is a red phosphor whose emission wavelength peak is in the range of 610 to 650 nm. The composition is represented by the following formula (1).

[Formula 1]

(In Formula 1, A is at least one selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ⁴⁺ , and M is a group 4 element and a group 14 element. It is at least one element selected from the group consisting of, and a satisfies 0<a<0.2.)

The half width of the emission peak of the KSF phosphor is 10 nm or less.

In addition, about this KSF phosphor, you may refer to Japanese Patent Application No. 2014-122887 for which the applicant of this application previously applied for a patent.

An example of the manufacturing method of a KSF phosphor is demonstrated. First, KHF ₂ , K ₂ MnF ₆ is weighed so as to have a desired composition ratio. The weighed KHF ₂ is dissolved in an aqueous HF solution to prepare a solution A. Further, the weighed K ₂ MnF ₆ is dissolved in an aqueous HF solution to prepare a solution B. Moreover, _the aqueous solution containing _H2SiF6 is prepared so that it may become a desired composition ratio, and it is set as the solution _C containing _H2SiF6 . And the solution B and the solution C are dripped, respectively, stirring the solution A at room temperature. After solid-liquid separation of the obtained precipitate, ethanol washing|cleaning is performed, and KSF fluorescent substance can be obtained by drying.

(MGF phosphor)

MGF is a red phosphor emitting deep red fluorescence. That is, the peak of the emission wavelength is 650 nm or more on the longer wavelength side than that of the KSF phosphor, and it is a phosphor activated with Mn ⁴⁺ . As an example of the compositional formula, it is expressed as 3.5MgO·0.5MgF ₂ ·GeO ₂ :Mn ⁴⁺ . The half width of the MGF phosphor is 15 nm or more and 35 nm or less.

In the MGF phosphor, a part of the Mg element of MgO in the composition is Li, Na, K, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, It may be substituted with other elements such as Yb, Lu, V, Nb, Ta, Cr, Mo, and W, and the luminous efficiency is improved by substituting a part of the Ge element in GeO ₂ with other elements such as B, Al, Ga, In, etc. may be improved. Preferably, by substituting both elements of Mg and Ge with both elements of Sc and Ga, respectively, the light emission intensity in the wavelength region of 600 to 670 nm called deep red can be further improved.

The MGF phosphor is a phosphor represented by the following formula (2).

[Formula 2]

(In Formula 2, x, y, z, a, b, c are 2.0≤x≤4.0, 0<y<1.5, 0<z<0.05, 0≤a<0.5, 0<b<0.5, 0≤ c<1.5, y+c<1.5, and Mt is at least one selected from Al, Ga, and In)

In the formula (2), when 0.05≤a≤0.3 and 0.05≤b<0.3, the luminance of the emitted red light can be further improved. In addition, about the MGF phosphor, you may refer to Japanese Patent Application No. 2014-113515 which the applicant of this application previously applied for a patent.

An example of the manufacturing method of the MGF fluorescent substance which concerns on embodiment of this invention is demonstrated. First, as raw materials, MgO, MgF ₂ , Sc ₂ O ₃ , GeO ₂ , Ga ₂ O ₃ , and MnCO ₃ are weighed so as to have a desired composition ratio. After mixing these raw materials, after filling this mixed raw material in a crucible, it can obtain by baking at 1000-1300 degreeC in air|atmosphere.

It is preferable that the ratio of the light emission intensity at the peak wavelength of the light emitting element to the light emission intensity at the peak wavelength of the red phosphor is 1st : 2nd = 100:55 to 70.

3) Green quantum dots

The green quantum dot 24 is a semiconductor material, for example, a compound semiconductor such as group II-VI, group III-V, or group IV-VI, more specifically, CdSe, core-shell type CdS _x Se _1-x /ZnS , and nano-sized particles such as GaP. The green quantum dots 24 have, for example, a particle diameter (average particle diameter) of 1 to 20 nm. The green quantum dot 24 emits, for example, green light whose emission wavelength peak is in the range of 510 to 560 nm. The half width of the emission peak of the green quantum dot 24 is as small as 40 nm or less, preferably 30 nm or less.

The green quantum dot may be surface modified or stabilized, for example, with a resin such as PMMA (polymethyl methacrylate). In this case, the particle diameter means the particle diameter of the core part containing the semiconductor material, which does not contain parts, such as resin attached for surface modification and stabilization.

4) light-transmitting material

The light-transmissive material 22 may transmit blue light, green light, and red light. The translucent material transmits preferably 60% or more, more preferably 70% or more, 80% or more, or 90% or more of the light emitted from the light emitting element 1 and incident on the translucent material 22 .

Preferable examples of the light-transmitting material 22 include high strain point glass, soda glass (Na ₂ O·CaO·SiO ₂ ), borosilicate glass (Na ₂ O·B ₂ O ₃ ·SiO ₂ ), and forsterite (2MgO·SiO ₂ ). ), lead glass (Na ₂ O·PbO·SiO ₂ ), and alkali-free glass can be exemplified. Alternatively, polymethyl methacrylate (polymethyl methacrylate, PMMA), polyvinyl alcohol (PVA), polyvinyl phenol (PVP), polyether sulfone (PES), polyimide, polycarbonate (PC), polyethylene Organic polymers (composed of a polymer material) exemplified by terephthalate (PET), polystyrene (PS), polyethylene naphthalate (PEN), cyclic amorphous polyolefin, polyfunctional acrylate, polyfunctional polyolefin, unsaturated polyester, epoxy resin, and silicone resin It has the form of a flexible plastic/film, a plastic/sheet, and a polymeric material such as a plastic substrate).

5) sealing resin

The sealing resin 12 may transmit blue light and red light, and preferably may also transmit green light. The translucent material transmits preferably 60% or more, more preferably 70% or more, 80% or more, or 90% or more of the light emitted from the light emitting element 1 and incident on the translucent material 22 .

As the preferable sealing resin 12, silicone resin, silicone-modified resin, epoxy resin, epoxy-modified resin, phenol resin, polycarbonate resin, acrylic resin, TPX resin, polynorbornene resin, or one or more of these resins are included. and resins such as hybrid resins to be used. Especially, a silicone resin or an epoxy resin is preferable, and especially the silicone resin excellent in light resistance and heat resistance is more preferable.

6) Resin package

The resin package 3 may be constituted by any kind of resin. Preferred resins include a thermoplastic resin or epoxy resin containing at least one of aromatic polyamide resins, polyester resins, and liquid crystal resins, modified epoxy resins, phenol resins, silicone resins, modified silicone resins, hybrid resins, acrylate resins, and urethanes. Resin, the thermosetting resin containing at least 1 type or more of these resins, etc. can be illustrated. The resin package 3 preferably contains a white resin. It is because more light which reached the resin package 3 among the light which advanced inside the sealing resin 12 can be reflected.

2. Embodiment 2

5 is a schematic cross-sectional view of a light emitting device 100A according to the second embodiment. In the light emitting device 100 described above, the sealing resin 12 contained the red phosphor 14 . However, in the light emitting device 100A, the translucent material 22 contained the red phosphor 14 instead of the encapsulating resin 12 containing the red phosphor 14 . Therefore, the red phosphor 14 and the green quantum dot 24 are arranged inside the light-transmitting material 22 , whereby the red phosphor 14 and the green quantum dot 24 are relative to the light-emitting element 1 . are located at approximately the same distance.

The light emitting device package 10A may have the same configuration as the light emitting device package 10 of the first embodiment except that the sealing resin 12 does not contain the red phosphor 14 . In addition, the green quantum dot containing layer 20A may have the same structure as the green quantum dot containing layer 20 of Embodiment 1 except that it contains the red phosphor 14 in addition to the green quantum dot 24.

As described above, in the light emitting device 100 according to the first embodiment, the red phosphor 14 is located closer than the green quantum dot 24 to the light emitting element 1, and the light emitting device according to the second embodiment In 100A, the red phosphor 14 and the green quantum dot 24 are located at approximately the same distance from the light emitting element 1 . Each embodiment has different advantages. The advantages are explained below.

1) Advantages of the light emitting device 100

6A and 6B are schematic cross-sectional views for explaining the advantages of the light emitting device 100, and FIG. 6A is a schematic cross-sectional view showing an embodiment in which the red phosphor 14 is disposed inside the sealing resin 12, and FIG. 6b is a schematic cross-sectional view showing an embodiment in which the red phosphor 14 is disposed inside the light-transmitting material 22 . As described above, the particle diameter of the red phosphor 14 is 20 to 50 μm, and the particle diameter of the green quantum dots 24 is 2 to 10 nm, and there is a large difference of about two orders of magnitude in the particle diameter.

6A and 6B are schematic diagrams for the purpose of showing more clearly the advantage of the light emitting device 100 based on the difference in particle size. Compared with FIGS. 1 and 5, the red phosphor 14 and the green quantum dots ( 24), the particle size difference is more clearly shown.

Reference numeral 114 in FIG. 6A schematically denotes red light (partial) emitted by the red phosphor 14X, which is one of the plurality of red phosphors 14 , and reference numeral 124, of the plurality of green quantum dots 24 . The green light (part) emitted by one green quantum dot 24X is schematically shown. Similarly, reference numeral 114A in Fig. 6B schematically denotes red light (partial) emitted by a red phosphor 14Y, which is one of the plurality of red phosphors 14, and reference numeral 124A, a plurality of green quantum dots 24 ), the green light (part of) emitted by the green quantum dot 24Y is schematically shown.

As shown in Fig. 6B, when a red phosphor 14 having a large particle diameter is disposed in the light-transmitting material 22, the green light 124A emitted from the green quantum dot 24Y is emitted by the red phosphor 14 existing in its path. ) and does not reach the top surface of the green quantum dot containing layer 20A (in FIG. 6B , red light 114A comes out from the top surface of the green quantum dot containing layer 20A, but green light 124A does not did not reach the top surface of the green quantum dot-containing layer 20A). When the red phosphor 14 having a large particle diameter exists in the green quantum dot-containing layer 20A, such scattering occurs in a part of the green light, which may cause a slight decrease in luminous efficiency.

On the other hand, as shown in Fig. 6A, the green quantum dot-containing layer 20 does not contain the red phosphor 14 having a large particle size, and contains only the green quantum dots 24 except for the light-transmitting material 22. not doing And, the possibility that green light traveling through the green quantum dot-containing layer 20 is scattered by the green quantum dots 24 having a very small particle diameter is quite low (in Fig. 6A, the red light 114 and the green light 124 are green outward from the upper surface of the quantum dot-containing layer 20). For this reason, higher luminous efficiency can be obtained.

2) Advantages of the light emitting device 100A

The green quantum dot containing layer 20A of the light emitting device 100A contains both the red phosphor 14 and the green quantum dot 24 as described above. Although the red phosphor 14 is less deteriorated by heat compared to the green quantum dot 24, by taking such a configuration, it is possible to suppress the transmission of heat from the light emitting element 1 to the red phosphor 14 as well. , the deterioration of the red phosphor 14 can be more reliably suppressed.

In addition, in order to arrange the red phosphor 14 and the green quantum dot 24 inside the light-transmitting material 22 , disposing the wavelength conversion material is solved only with the light-transmitting material 22 , so that the sealing resin 12 is red in color. Since it is completed without arranging the phosphor 14, the manufacturing process is simplified.

In addition, as described above, in the light-emitting device 100A, the light-transmitting material 22 of the green quantum dot-containing layer 20A contains the red phosphor 14, and the sealing resin 12 of the light-emitting device package 10A is a red phosphor. Although (14) is not included, both the light-transmitting material 22 of the green quantum dot-containing layer 20A and the sealing resin 12 of the light-emitting element package 10A may contain the red phosphor 14 .

3. Embodiment 3

7 is a schematic cross-sectional view showing a liquid crystal display 200 using the light emitting device 100B according to the third embodiment. The light emitting device 100B includes a light emitting device package 10 , a green quantum dot containing layer 20 , and a light guide plate 52 disposed between the light emitting device package 10 and the green quantum dot containing layer 20 .

In the embodiment shown in FIG. 7 , the light guide plate 52 is disposed between the sealing resin 12 of the light emitting device package 10 and the green quantum dot-containing layer 20 . More specifically, the sealing resin 12 is disposed to face one side surface of the light guide plate 52 , and the green quantum dot-containing layer 20 is disposed to face the upper surface of the light guide plate 52 . Although the light emitting element package 10 is a top view type in embodiment shown in FIG. 7, it is not limited to this, You may have other forms, such as the side view type mentioned above.

The light emitting device 100B reflects upwardly the light reaching the lower surface of the light guide plate 52 among the light incident from the light emitting device package 10 to the light guide plate 52 , and faces the upper surface of the light guide plate 52 . A reflecting plate (reflector) 51 may be provided on the lower surface of (52).

In the embodiment shown in Fig. 7, the light emitting device package 10 is disposed to be spaced apart from the light guide plate 52, but is not limited thereto. The light emitting device package 10 and the light guide plate 52 may be brought into contact with the side surface of the 52 , for example.

The green quantum dot-containing layer 20 may be disposed in contact with the upper surface of the light guide plate 52 , or may be disposed apart from the light guide plate 52 .

On the green quantum dot-containing layer 20 , a lower polarizing film 53A is disposed. A liquid crystal cell 54 is disposed on the lower polarizing film 53A, and a color filter array 55 is disposed on the liquid crystal cell 54 . The color filter array 55 transmits only light of a specific color, such as the red color filter unit 55A, the green color filter unit 55B, and the blue color filter unit 55C, corresponding to other colors. A plurality of types of color filter units are provided. An upper polarizing film 53B is disposed on the color filter array 55 .

Next, the operation of the liquid crystal display 200 will be described.

A part of the blue light emitted by the light emitting element 1 comes out of the sealing resin 12 . In addition, a part of the blue light emitted by the light emitting element 1 is absorbed by the red phosphor 14 disposed in the sealing resin 12, and red light is emitted from the red phosphor 14, and this red light is transmitted to the sealing resin ( 12) comes from That is, from the light emitting device package 10, purple light in which blue light and red light are mixed is emitted, and this purple light (blue light + red light) passes through the light guide plate 52 to the green quantum dot-containing layer 20. enter A part of the blue light entering the green quantum dot-containing layer 20 is absorbed by the green quantum dot 24, and the green quantum dot 24 emits green light. As a result, from the upper surface of the green quantum dot-containing layer 20, white light in which blue light, green light, and red light are mixed is emitted, and the white light enters the lower polarizing film 53A. A part of the white light (blue light + green light + red light) entering the lower polarizing film 53A passes through the lower polarizing film 53A and enters the liquid crystal cell 54 . Part of the white light entering the liquid crystal cell 54 passes through the liquid crystal cell 54 and reaches the color filter array 55 .

Each of the blue light, green light and red light that has reached the color filter array 55 may pass through the corresponding filter unit. For example, red light passes through the red color filter unit 55A, green light passes through the green color filter unit 55B, and blue light passes through the blue color filter unit 55C. A portion of each of blue light, green light, and red light passing through the color filter array 55 passes through the upper polarizing film 53B. Accordingly, the liquid crystal display 200 can display a desired image.

As described above, the red light emitted by the red phosphor 14 and the green light emitted by the green quantum dots 24 have a narrow half-width of their emission peaks, and thus have high color purity. In addition, since more light can pass through the red color filter unit 55A and the green color filter unit 55B, efficiency can be improved.

1: light emitting element
3: Resin package
5: lead
10, 10A: light emitting device package
11: semiconductor layer
12: sealing resin
13: light-transmitting substrate
14: red phosphor
15: plating layer
16: filler
20, 20A: layer containing green quantum dots
22: light-transmitting material
24, 24X, 24Y: Green quantum dots
51: reflector
52: light guide plate
53A: lower polarizing film
53B: upper polarizing film
54: liquid crystal cell
55: color filter array
55A: red color filter unit
55B: green color filter unit
55C: blue color filter unit
100, 100A, 100B: light emitting device
114, 114A: red light
124, 124A: green light
200: liquid crystal display

Claims (10)

A sheet-shaped or film-shaped light-transmitting material, comprising:
a red phosphor for emitting red light by absorbing a portion of blue light emitted by the light emitting device; and
A green quantum dot that emits green light by absorbing a part of the blue light emitted by the light emitting element
A light-transmitting material comprising: The light transmitting material according to claim 1, wherein the light transmitting material is an organic polymer. The light-transmitting material according to claim 1, wherein the light-transmitting material is a polymethyl methacrylate resin. The light-transmitting material according to claim 1, wherein the half-width of the emission peak of the red phosphor is 35 nm or less. The light-transmitting material according to claim 1, wherein a peak of the emission wavelength of the green quantum dot is 510 to 560 nm. The light-transmitting material according to claim 1, wherein the half-width of the emission peak of the green quantum dot is 40 nm or less. The light-transmitting material according to claim 1, wherein the green quantum dots have a particle diameter of 1 to 20 nm. The light-transmitting material according to any one of claims 1 to 7, wherein the red phosphor is at least one of a KSF phosphor and an MGF phosphor. The light-transmitting material according to claim 8, wherein the red phosphor is a KSF phosphor, and the composition thereof is represented by the following formula (1).
[Formula 1]

(In Formula 1, A is at least one selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ⁴⁺ , and M is a group 4 element and a group 14 element. It is at least one element selected from the group consisting of, and a satisfies 0<a<0.2.) The light-transmitting material according to claim 8, wherein the red phosphor is an MGF phosphor, and the composition thereof is represented by the following formula (2).
[Formula 2]

(In Formula 2, x, y, z, a, b, c are 2.0≤x≤4.0, 0<y<1.5, 0<z<0.05, 0≤a<0.5, 0<b<0.5, 0≤ c<1.5, y+c<1.5, and Mt is at least one selected from Al, Ga, and In)

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